Powering the Future: A Scientist's Guide to Energy Independence

by Daniel B. Botkin

  • Fusion: This actually doesn’t exist yet, and may never, so it cannot now be considered a potential solution.

  The reactor is a complicated machine, full of pumps, pipes, very corrosive materials, lots of wires, and a lot of mechanisms to shut things down if something goes wrong. In the reactor core, fuel pins, consisting of enriched uranium pellets in hollow tubes (3–4m long and less than 1cm, or 0.4 in., in diameter), are packed together (40,000 or more in a reactor) in fuel subassemblies. A minimum fuel concentration is necessary to keep the reactor critical—that is, to achieve a self-sustaining chain reaction. A stable fission chain reaction in the core is maintained by controlling the number of neutrons that cause fission. The control rods, which contain materials that capture neutrons, are used to regulate the chain reaction. As the control rods are moved out of the core, the chain reaction quickens; as they are moved into the core, the reaction slows. Full insertion of the control rods into the core stops the fission reaction.

  The coolant removes heat produced by the fission. The rate of heat generation in the fuel must match the rate at which heat is carried away by the coolant. All major nuclear accidents have occurred when something went wrong with the balance, allowing heat to build up in the reactor core.

  In a meltdown, the nuclear fuel becomes so hot that it creates a molten mass that breaches the walls of the reactor and contaminates the environment.

  Nuclear power reactors, each of which produces about 1,000MW of electricity, require an extensive set of pumps and backup equipment to ensure that adequate cooling is available to the reactor. Smaller reactors can be designed with cooling systems that work by gravity and are thus not as vulnerable to pump failure caused by power loss. Such cooling systems are said to have passive stability, and the reactors are said to be passively safe.

  The bottom line

  • Conventional nuclear power plants are not a short-term solution to the energy problem, because they take too long to build. They are also not a long-term solution, because nuclear plants have short lives and their fuel is a rare mineral that will run out in decades.

  • Their radioactive wastes, however, will be with us for thousands of years, and there is no satisfactory solution to dealing with these wastes.

  • Although governments and international agencies say nuclear waste is being handled safely, evidence suggests the contrary. In particular, ground water is more erosive than engineers expected and has corroded some facilities, allowing radioactive water to escape into the ground and then contaminate surface water.

  • Nuclear power is expensive, but many of the costs are indirect and thus not evident: for example, development of atomic reactors has been funded primarily by governments, as is dealing with the wastes and the cleanup when contamination occurs.

  • No insurance company will insure a nuclear power plant. As a result, governments are responsible for any damage and lawsuits—another hidden cost.

  • Nuclear power plants have had only a few major accidents, but these have been costly.

  • Exploration and prospecting for uranium ore will probably increase greatly, especially in remote, relatively unexplored areas, raising new problems for conservation of biological diversity, along with environmental pollution and, locally, human health.

  • In sum, nuclear energy is a cure worse than the disease. And since there are alternative sources of abundant energy that don’t pose the hazards of nuclear power, why take the unnecessary risks that it entails?

  Section II. New energy sources

  Americans built great public work projects to pull ourselves out of the Great Depression. The hydroelectric projects on the Columbia, the Colorado, and the Tennessee rivers are witness to what we can accomplish when we put our minds to it. We rose to the challenge of fascism in WWII. We belatedly granted civil rights to all our citizens in the 1960s and in the modern era we have pushed cigarette smoking to the fringes of society.

  Our next great challenge will be the rapid conversion of American electricity supply from fossil fuels to renewable sources of energy, and the conversion of the bulk of personal transportation to electric vehicles. In doing so we can transform society and reindustrialize the continent’s heartland.

  —Paul Gipe, wind energy expert

  If it makes people feel good to shove up a windmill or put a solar panel on their roof, great, do it. It’ll help a little bit, but it’s no answer at all to the problem.

  —James Lovelock, internationally known environmental scientist and father of the Gaia hypothesis about how all life on Earth is connected

  If experts like these two can disagree as much as they do, it’s no wonder that you may be confused about whether alternative forms of energy can meet our needs. In this section, we explore the major sources of renewable alternative energy. By the end of this section, you can better choose between the assertions of the wind energy expert Paul Gipe and the internationally famous environmental scientist James Lovelock, and understand which are the better alternatives. Should we turn to wind, solar, ocean, and biofuels—or perhaps a combination of these and other energy sources? If so, what would be the best combination?

  To make a start at considering these alternative sources, we need to look again at a chart you saw earlier, showing world energy use and how much each of these alternatives contribute today worldwide (Figure SII-1). This helps you to see how much they would have to grow to become major energy sources that could replace fossil fuels to a significant extent.

  Figure SII.1 World energy use 2010 by fuel type

  In the United States, alternative renewable energy sources, a group that for our purposes includes wind, solar, and biofuels, today provide 3.7% of the energy, but biofuels, taken together, are the largest contributor. These include wood cut and burned, waste such as cooking oil that is later burned, and crops grown to be converted directly into fuel. All renewable energy sources, which typically include the three just mentioned—wind, solar, and biofuels—as well as freshwater energy and geothermal energy, provide 7% of the energy in the United States. If we focus only on solar, wind, and biofuels, we find that firewood provides about half, crops grown as fuels 23.3%, and wastes 10%. Solar and wind are a small part of this group, 7% and 2%, respectively (Figure SII.2).

  Figure SII.2 U.S. renewable energy 20072 (Source DOE EIA)

  This suggests that all the renewables together—conventional and alternative—play rather small roles in energy supply today. When, if ever, will renewable energy provide most, or at least half, of the world’s energy? And at what costs, both economic and in terms of undesirable effects on the environment and the lives of people?

  We can see the beginning of an answer in the fact that use of renewable energy is increasing. Between 2005 and 2006, it increased 7%, while total energy use actually declined 1% (mainly due to reduced use of fossil fuels).1 But if we continue to move away from fossil fuels, will we face a future in which our energy supply and per-person use is so limited that we must accept a decline in our overall standard of living? This section helps to answer these questions.

  6. Wind power

  Figure 6.1 Under a hazy sun, a pair of pronghorn antelope graze in a west Texas field as wind turbines generate electricity in the background. (©iStockphoto.com/chsfoto)1

  Key facts

  • Wind is the cheapest alternative energy source. Electricity from wind energy costs between 4.5 cents and 7.5 cents per kilowatt-hour, making it cost-competitive with fossil fuels.

  • The windiest 20 states have enough wind energy to potentially provide one-third to one-half of the total U.S. energy use, and all of its electricity, now and in the next 40 years.

  • Today’s wind turbine is as tall as a 22-story building and generates enough electricity for 500 modern U.S. homes.

  • Each of these modern wind turbines cost about $2 million to install, all costs included.

  • Worldwide, wind power provides just a few percent of the electricity, but installations are increasing rapi
dly, and in some nations wind provides as much as 40% of the energy. Germany gets 5% of its electricity from the wind.

  • The best sites for wind power in the U.S. are along the coasts, including just offshore and in the coastal mountains of the Pacific states, and also in the Midwest, especially in a north-south belt stretching from eastern Montana and Minnesota to the Texas panhandle.

  • Wind energy is also a great benefit in the developing nations and rural areas, and for the poor, especially where other forms of energy are not easily available. In these situations, small windmills that generate electricity are becoming an important part of self-help to raise standards of living.

  • In the U.S., almost 7,000 small windmills are sold each year for generating electricity on farms and for individual homes.

  Sailboats and windmills are ancient

  Opinions about wind energy have blown hot and cold, variable as the wind itself, viewed in some centuries as important and fashionable, in others not so much. A drawing of a sailboat appears on an Egyptian pottery vessel 4,000 years old. The earliest known windmills were Persian, dated as early as 900 BC.

  Along with watermills, windmills were important sources of energy in the Middle Ages and the Renaissance. They continued to be important on a large scale into the early part of the scientific-industrial age in the 19th century, and locally, mainly in rural areas, they remained important for pumping water for some time into the 20th century. One history of wind power states that “between 1850 and 1970, over six million mostly small (1 horsepower or less) mechanical output wind machines were installed in the U.S. alone,”2 pumping water for cattle and people. They are familiar today as decorative, if no longer functioning, landmarks of the rural countryside.

  The first windmills to generate electricity were built at the end of the 19th century. They were overshadowed by the invention of the coal-powered steam engine and petroleum-powered gasoline and diesel engines, which could run almost anywhere, anytime, a convenience that soon came to be considered a necessity and just couldn’t be beat. Few today know about the first windmill to generate electricity, which was built in 1888 in Cleveland, Ohio. Know as the Brush postmill, it made use of modern metals, which provided greater strength and allowed greater size than the earlier picturesque wind machines. Its “pinwheel” blades had a diameter of 56 feet (17 meters). It was new and impressive, but it couldn’t compete with coal, oil, and steam engines, and this kind of machine did not become popular.3

  Winds of change have freshened quickly for wind power in the 21st century, with renewed enthusiasm for it perhaps best illustrated by a completely new kind of sailing ship, the MV Beluga SkySails, which completed its maiden voyage of 11,952 nautical miles on March 14, 2008, sailing from Bremen, Germany, to Venezuela and back carrying heavy industrial equipment (Figure 6.2).

  Figure 6.2 Wind power is becoming so popular that it is even making a comeback as a way to propel ships. Here a new kind of sail, actually a cable-tethered kite, helps pull a new ship through the ocean. (Copyright SkySails)4

  The Beluga SkySails is novel in two ways. First, it did not use a set of fixed masts with traditional sails that had to be monitored constantly and their settings changed with each variation in the wind, thereby requiring either a large crew or sophisticated and expensive equipment. Instead, this ship flew a huge kite that spread out over more than 160 square yards. Flying high in the sky and attached to the hull by stout cables, it caught more reliable winds aloft than occur at the surface and required only a flexible cable to tether the kite-sail to the ship (Figure 6.2).

  Second, and almost as important, wind provided only part of the power—on the maiden voyage 20%—the rest coming from standard marine diesel engines. With the Beluga SkySails it isn’t an either-or situation, either alternative fuel or fossil fuel, but an integration of several energy sources. Diesel provided the steady energy, while the kite-sail helped when wind was available, reducing fuel costs by $1,000 a day. With this saving and also saving the expense of a large crew, Beluga SkySails was an economic success. At the end of the voyage, the ship’s captain, Lutz Heldt, said, “We can once again actually ‘sail’ with cargo ships, thus opening a new chapter in the history of commercial shipping.”

  It’s worth repeating two key insights that come from this design, which are important as we work out how we are going to develop energy systems (arrangements that use a variety of sources of energy together) and turn more and more to alternative energy. The first insight is simply to integrate different forms of energy, making use of the strengths of each. In this ship’s case, the combination is the reliability of internal combustion engines burning fossil fuel (or possibly in the future a biofuel), along with free wind energy. The second insight is the kite design itself, which instead of working against the natural forces, like the rigid masts of a sailing ship, is flexible, giving, shifting, and moving with the wind even as it helps pull the ship through the water. Therefore, it is much less likely to be damaged by storms.

  Stephan Wrage, the SkySails company’s managing director, said, “In the future, depending on the route and weather conditions, we’ll be able to post fuel savings of between 10% and 35% using wind power.” The ship is the product of private industry, co-funded with 1.2 million euros from the European Union’s “LIFE” program.5

  Can wind energy be a major player in the United States or on the world stage?

  SkySails is intriguing, but does it really signal that wind power can be an important part of our energy supply? Or is it another appealing curiosity?

  With worldwide concern over global warming, some people feel that the only question of interest is the global one: What kind of energy will make a dent in worldwide use of fossil fuels and the release of greenhouse gases? But many people in the world live where energy is scarce, expensive, and a fundamental cause of poverty. For them, even if an alternative source of energy can’t solve the entire world’s problem, it might be valuable locally. I consider both possibilities.

  The largest wind energy installation in the United States east of the Mississippi is the Mountaineer Wind Energy Center in Tucker and Preston counties, West Virginia, owned and operated by Florida Power & Light and producing electricity since 2002. It has 44 big machines, which, by the way, are no longer called by their traditional and humbler name, windmills. These are wind turbines, each 228 feet high, the height of a 22-story building. Together, these turbines have the capacity of 66 million watts and in a typical windy year can produce 170 million kilowatt-hours, which is enough electricity for 22,000 homes. Each turbine is installed on 100 acres, and the entire facility takes up 4,400 acres, or just under 7 square miles.6, 7 There are larger wind farms in the Midwest and Far West, such as one of the first, the Tehachapi Wind Farm in California (Figure 6.3).

  Figure 6.3 Here are some of the 5,000 wind turbines on the Tehachapi Wind Farm in California, east of the San Francisco Bay, and one of the largest collections of wind generators in the world. Several private companies share ownership. In total, these turbines produce enough electricity for 350,000 people. (DOE Photograph http://www.doedigitalarchive.doe.gov/SearchImage.cfm?page=search)8

  Wind energy potential in the United States

  According to the American Wind Energy Association, the windiest 20 states have wind energy to potentially provide one-third to one-half of the U. S. total energy use, and two and one-half times as much energy as all of present electricity generated. Could enough wind turbines be manufactured in the United States? One analysis concludes that

  for the wind to generate ~1,000 TWh/yr, we would need to install ~500,000 MW of wind generating capacity across the breadth of the country....Americans drive ~5,000 billion km/yr. To power this fleet with electric vehicles would require a huge new supply of clean electricity. Current electric vehicles can travel ~0.25 km per kilowatt-hour of electricity supplied. Thus, converting passenger vehicles to electricity will require the generation of ~1,000 TWh/yr. Using the same assumptions as before, this would d
emand the installation of ~500,000 MW of new wind generating capacity....There’s more than ample land area in the US for such a large number of wind turbines. Even with a very open spacing, for example 8 rotor diameters by 10 rotor diameters apart, ~1 million MW would require little more than 3% of the land area of the lower 48 states. And of this land, the wind turbines would only use about 5% for roads and ancillary facilities.

  Moreover, the US has the manufacturing capacity to build such a large number of machines within less than two decades.

  Every year American manufacturer’s of heavy trucks churn out ~300,000 vehicles. Each heavy truck is the equivalent of a 500,000 watt wind turbine. Thus, heavy truck manufacturers alone build the equivalent of ~150,000 MW/yr.